Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Description highlights that the 'returned secret is a high-privilege credential; do not log or expose it' — a valuable safety disclosure. It also states the return type and token cost. However, since no annotations are provided, the description does not mention permissions required, reversibility, or side effects beyond creation; it relies on the obvious 'create' semantics.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Description is compact, with each section (action, sensitive warning, prerequisite, return, cost) serving a distinct purpose. Clear formatting with line breaks and bold makes it scannable.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a mutation tool with zero annotations and 9 parameters, the description provides key context: sensitivity, prerequisite, instance selection, and return type. The output schema covers return details, and params are fully specified in schema. Missing alternative guidance is a minor gap, but overall sufficient.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Input schema already describes all 9 parameters with 100% coverage, so the description adds little beyond the 'clerk_instance_id' guidance already present in the schema. The description doesn't enrich parameter meanings beyond what the schema provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states 'Create an API key in a connected Clerk application' — a specific verb and resource. Among many create_* siblings, it does not explicitly distinguish from token creation tools like create_m2m_token or create_session_token, but the target is unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit prerequisite: 'Call clerk.get_connected_accounts first.' Also explains instance targeting: 'Pass clerk_instance_id to target a specific connection, or omit it to use the default account.' No mention of when to choose this over alternative credential-creation tools, but the context is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.